Varroa mite

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Varroa mite
Varroa females

Varroa females

Systematics
Class : Arachnids (arachnida)
Order : Mites (acari)
Subordination : Mesostigmata
Family : Varroidae
Genre : Varroa
Type : Varroa mite
Scientific name
Varroa destructor
Anderson & Trueman , 2000

The Varroa mite ( Varroa destructor ) is a (as adult females) about 1.1 millimeters long and 1.6 millimeters wide mite from the family Varroidae that as a parasite of honey bees ( Apis mellifera and Apis cerana lives). The mite develops and multiplies in the capped brood in the beehive . The infestation of bee colonies by the mite is as Varroose (old name: Varroa ), respectively. Varroa destructor is considered the most important bee pest worldwide.

In Austria the animal disease varroose is notifiable, in Switzerland under Gr. 4 Diseases to be monitored (mandatory reporting) classified. In Germany it is regulated in Section 15 of the Bee Disease Ordinance, but due to its ubiquity there is no obligation to notify or report.

Origin of name

The genus is named after the Roman scholar Marcus Terentius Varro (116-27 BC), who wrote writings on agriculture.

anatomy

Varroa mite on a bee in the scanning electron microscope

  • Ventral side of a varroa mite. Four legs each on the left and right of the body, the first pair of legs being transformed into sensory organs. In between the lancing and suction apparatus.

  • Varroa mite, which all legs of a honeybee were bitten.

The species is characterized by a distinctive sexual dimorphism . The males are considerably smaller and narrower, more triangular-teardrop-shaped, their legs are significantly longer in relation to their body size. They are less sclerotic and light yellow. 80% of all Varroa mites are female, only they leave the brood comb and thus appear, while the males remain there after mating and die.

As with most mites, the body of the varroa mite is divided into two sections called idiosoma and gnathosoma . The gnathosoma, on which the mouthparts sit, is relatively small and shifted to the abdomen between the hips ( coxes ) of the first pair of legs; it is not visible when viewed from above. The idiosoma is covered on the dorsal side by an undivided, heavily sclerotized shield that is red-brown. On the ventral side there are several red-brown ventral shields that are connected by sutures. The back shield of the female is transversely oval and significantly wider than it is long, it is densely covered with bristles (setae). The mouthparts consist of two pedipalps that serve as sensory organs and two tripartite chelicerae that serve as food intake. The last chelicerene member is designed as a movable, toothed cheliceric finger, with which the mite can cut open the body wall of its host bee. The second, immobile chelicerene finger is missing (family characteristic). The mite has four pairs of legs, the first of which is six-limbed, the rest are seven-limbed. The short, strong legs have no claws; instead , structures called apotles sit on the surface and are used to hold on. The first pair of legs stretched forward serves as a sensory organ. In addition to various sensory hairs that serve as mechano and chemoreceptors, it has a pit-like sensory organ, similar to the Haller organ in ticks .

On the ventral side of the idiosoma there is an elongated depression, the peritrema. This is connected to the stigmas of the tracheal system, which sit on the outside of the abdomen, and serves as a breathing organ.

Life cycle and development

The species is parasitic in all stages of life and never lives in the wild, but only inside beehives or on bees. All nymph stages and the males live inside of capped brood cells. Only the females occur outside the cells. They then usually sit on the ventral side of the abdomen of adult bees, mostly drilled into the intersegmental skin between the ventral shields, but they can also sit elsewhere on the body. They are well protected against the cleaning behavior of the bees by the fixed back shield. The transmission of the Varroa mite to other bee colonies is naturally only possible with direct physical contact by misoriented or food-consuming workers in unfamiliar hives. The adult Varroa females suckle on the workers to eat, but for their reproduction they are bound to the brood combs of the beehive.

The Varroa females leave the adult bee while it covers a brood cell with an old larva (fifth larval stage) that is ready to pupate. Although various chemoreceptors and behavioral experiments have shown that bee larvae, cocoon material and food supplies have an attractive effect on the mite, the triggering stimulus is not yet understood in detail. The brood of drones is up to eight times more infested than that of worker women, but queen brood almost never. The mite migrates through the space between the bee larva and the cell wall to the cell floor, which contains the remaining food supply, possibly in order to evade defense behavior of the bees. The mite begins to suckle on the bee larva when the food supply is used up. It lays its first egg around 50 hours after being capped. This remains unfertilized and develops into a Varroa male due to sex determination via haplodiploidy . The following eggs, which are laid about 30 hours apart, are fertilized and therefore develop into females. A mother mite lays five female eggs in worker larvae and six in drone larvae.

The first stage of development of the Varroa is a six-legged larva that develops completely inside the egg shell. In the second stage of development, this results in an eight-legged protonymphe that hatches from the egg. It sheds its skin in the third stage of development, the deutonymph, from which the new generation of adult mites emerges. Both nymph stages become immobile towards the end of their growth period, this immobile transition stage is called chrysalis . While the nymphs are white, the final resting stage ( Deutochrysalis ) already has the brown color of the adult female mites.

Neither nymphs nor males of the Varroa mite are able to eat independently because their mouthparts can not penetrate the integument of the bee larva; in the male, these are transformed into specialized mating organs and cannot be used for food production. They rely on the mother mite to inflict wounds on the bee larva or pupa to suckle. These are usually on the fifth segment of the host bee.

The female mites become sexually mature immediately after moulting into adult animals. The siblings mate with each other several times in the days before the bee hatches. The male mates with the female inside the still capped brood cell by transferring a spermatophore directly into the female's gonophore , which it stores in a spermatheca in order to be able to fertilize the other eggs with it. The male then dies without ever leaving the cell. The female mites leave the cell together with the hatching bee after about 12 days, while the male remains. The mother animal can also leave the cell for a second, and less often even a third, such reproductive cycle. Despite the relatively moderate reproduction rate and a not inconsiderable proportion of mites that do not reproduce at all for unknown reasons, bee colonies collapse under moderate climatic conditions about three to four years after being infected with Varroa destructor . In contrast, the mite population grows more slowly in warmer, subtropical or tropical climates.

Distribution and host types

Varroa destructor (lat., Dt. Destructive mite ) was described by Anderson and Trueman in 2000. Previously, the mites were included in the long-known species Varroa jacobsoni Oudemans, 1904, which only occurs in Southeast Asia. The species is therefore listed under this name in older literature.

The original host of Varroa destructor is the eastern honey bee ( Apis cerana ). In this species, only the larvae are attacked by drones; they do not develop on workers. The mite species was restricted to tropical East Asia, where three other species of the genus live west to Nepal. The species was passed on to the western honey bee, Apis mellifera , through cultured bees that had been introduced into the home of Apis cerana . Additional hosts of Varroa destructor are not known.

Molecular genetic studies of Varroa mites identified different strain lines of the species and its closely related sister species Varroa jacobsoni , which colonize different parts of their natural range. Only two of these types have passed on to Apis mellifera , of which only one (the so-called Korean haplotype) has been transported worldwide. The mites, which are widespread worldwide, are, in contrast to those of their homeland of origin, genetically so uniform that they can be regarded as clones .

Today Varroa destructor is distributed worldwide with the exception of Australia and the Antarctic. The species was mainly carried off by shipping colonies of bees and queens. The first evidence from the Russian Pacific coast comes from 1952, from Japan from 1958. In Europe it was first found in 1967 in Bulgaria. The first German proof dates from 1977.

In many parts of Europe, beekeepers are forced to migrate with their colonies because of the large monocultures of industrialized agriculture, which promotes the rapid spread of the parasite.

Varroa mites on a beehive
Varroa mite on a flying honey bee

Disease and bee deaths

Mites weaken the bees in various ways. By sucking out the hemolymph , the infected larvae lose weight directly, the hatched bees remain around a tenth smaller than healthy animals. According to a recent study , when they parasitize on adult bees , the majority of food is adipose tissue . The infected animals have a significantly shortened life span. They have poorer learning achievements and more often do not return to the hive.

In addition, harmful viruses (e.g. Deformed Wing Virus ) are transmitted by the mite infestation . Of the 18 pathogenic viruses known to be found in honey bees, five have been shown to be transmitted by varroa mites as vectors. In addition, previously suppressed pathogen infestation can now become virulent due to the damage to the bee's immune system. It is usually assumed that the damage caused by the mite itself, but rather the spread and promotion of the pathogens, is responsible for the eventual collapse of the bee colony. Infestation with the single cell Nosema apis or other Nosema species may also contribute to this.

The varroa mite is one of the main causes of the epidemic bee deaths that have occurred in Germany for several years in autumn or winter , especially when exposed to neonicotinoids .

Resistances

Varroa destructor damages its original host, the Eastern honey bee ( Apis cerana ) only mildly and insignificantly (varroa tolerance). In this species only drone larvae are attacked. The bees are more successful in removing the parasite, and heavily infested drones remain in the cell without hatching, which limits the mite reproduction. In the western honey bee ( Apis mellifera ) these defense mechanisms , which are probably caused by coevolution , are largely absent .

However, even among the colonies of the western honeybees, some were found that naturally cope better with the parasite infestation than others. It is well documented that Africanized honey bees are more resistant than the ancestral form. The same applies to the Sicilian honey bee ( Apis mellifera siciliana ). In Europe, there are populations in Gotland (Sweden) and Avignon (France) which, unlike usual, can tolerate mite infestation for many years. There are breeding programs for so-called VSH bees ( English Varroa Sensitive Hygiene bees ). In the USA, two strains have been developed that can detect and remove damaged pupae under lids before the infestation spreads further. The “IN” / Indiana strain is being developed at Purdue University to develop lines that clean up adherent Varroa mites and kill them with bites. Suppressed mite multiplication is possible, for example, by “recapping” the brood cells. Russian strains (Primorsky bees) also have greater resistance than most Western European breeding lines.

The breeding of resistant or tolerant lines is considered to be the only long-term promising method of combating the mite and is therefore attempted at various points by crossing more resistant lines into the strains usually used.

Combat

In any case, it is important to assess the severity of the infestation by means of regular checks. This is done by means of litter diagnosis by counting the number of dead mites that have fallen to the bottom of the beehive per day. If 5 to 10 mites fall per day in July, the infestation can already be critical. The infestation of a bee colony can be calculated more precisely with the Edlinger Varroa indicator. From the date and the number of dead mites for several days, the indicator calculates an approximate infestation strength and how many mites can be controlled with one treatment. A distinction is also made between a colony of bees with and without brood. The indicator was developed over several years by the beekeeper Kurt Edlinger. Another diagnostic option for infestation control is the powdered sugar method . With the help of this method, the intensity of the infestation can be determined quickly and very precisely. If powdered sugar were used for therapy, this would have to be assessed according to the Medicines Act.

Chemical control methods

Nassenheider evaporator for the treatment of varroosis

The control of mites with acaricides , especially phosphoric acid esters and pyrethroids , was one of the first control strategies. Numerous Varroa destructor populations are now resistant to a large number of these preparations. Other disadvantages of acaricide treatment include residues in wax and honey and damage to bees from joint exposure to other chemicals common in the environment.

Some good successes have been reported for the use of organic acids such as formic acid (liquid; miscible with water), lactic acid (as a racemate liquid; miscible with water) and oxalic acid (solid; up to 10% soluble in water). Lactic acid is mainly used in summer for the initial treatment of young colonies (offshoots), as long as they are still brood-free; winter treatment with lactic acid is possible and very successful. Formic acid is introduced into colonies in a number of ways.

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For the first time, new drugs with formic acid enable treatment during the forage period, during which the honey can then be harvested.

The bee institutes are currently warning against this use because there is not yet sufficient experience with the remaining amount of acid residues in honey. MAQS (MiteAwayQuickStrips, Gel + Formic Acid) has an exponential effect, especially on the first day, which in 2014 also led to losses of queens. Oxalic acid is usually introduced in liquid form into the honeycomb lanes of the lower brood margin in November or December. These three acids or their salts occur naturally in the metabolism of plants and animals and even in some types of honey. Another method is based on the use of essential oils with thymol .

However, these agents can only be used in periods without brood, the success also depends on the vapor pressure of the substance in the hive. But there is neither resistance nor residues in the honey.

A completely newly researched approach is to feed the bees with lithium chloride ; this promises to kill the mites that sit on it without harming the bees. However, the treatment must first be tested further in order to rule out effects on the brood and residues in the honey and to determine the dosage.

Agents approved against varroosis in Austria

Five veterinary medicinal products have been approved in Austria since July 11, 2014:

  1. AMO Varroxal 85% formic acid solution for evaporation in the beehive for honey bees
  2. Apiguard - Gel for bees (prescription and pharmacy only)
  3. APILIFE VAR - impregnated strips for the beehive for honey bees
  4. Dany's BienenWohl - 3.5% (m / m) oxalic acid dihydrate solution for drizzling honey bees
  5. THYMOVAR; 15 g strips for the beehive, for honey bees

Agents approved against varroosis in Germany

Eleven drugs are approved in Germany:

  1. Pericin (active ingredient: Coumaphos )
  2. Bayvarol (pyretroid), (active ingredient: flumethrin )
  3. Apiguard (thymol)
  4. Thymovar (thymol)
  5. ApiLiveVar (thymol and others)
  6. Lactic acid 15% ad us.vet.
  7. Formic acid 60% ad us.vet.
  8. MAQS = MiteAwayQuickStrips (gel + formic acid)
  9. Oxalic acid hydrate solution ad us.vet.
  10. Oxuvar ad us.vet. (Oxalic acid)
  11. Apitraz and Apivar (Amitraz) (prescription only)

The preparations based on formic acid, lactic acid and thymol are freely available and do not require an entry in the inventory. All others require a prescription and a pharmacy.

In a country of the European Union (EU), in the event of a therapy emergency (definition in AMG ), priority must be given to using an agent that is approved in an EU country. Since July 11, 2014, 85% formic acid may therefore only be used in Germany as "AMO Varroxal 85% formic acid solution" and only if it is prescribed by the veterinarian in the event of a therapy emergency and because it has been used in the EU country Austria (there freely available) is approved as "Varroxal".

Agents approved against varroosis in France

In France, seven remedies were approved in 2016 ( disposants d'une AMM ):

  1. Apivar (active ingredient: Amitraz )
  2. ApiLiveVar (thymol, eucalyptol, menthol, camphre)
  3. Apiguard (thymol)
  4. Thymovar (thymol)
  5. Apistan (tau fluvalinate)
  6. MAQS = MiteAwayQuickStrips (gel + formic acid)
  7. Apitraz (Amitraz)

Biological control methods

Drone frame (pikeperch format), 21 days after insertion.
There are around 1300 capped drone cells on both sides. In between there are still a few uncovered cells.

The drone brood is about 5 to 10 times more likely to be attacked by the Varroa mite than the worker bee brood , and the mites can multiply more frequently due to the longer breeding season. The beekeepers use this to fight varroa by using so-called drone frames. During the growth phase of the bee colony (spring to early summer), empty frames are hung in the lowest brood box of a magazine hive , which the bees preferably expand with larger cells in which drone larvae develop after the queen has laid their eggs. The already capped drone brood is then removed together with the mites in it shortly before hatching or treated hypothermically (frozen). The removal or the targeted hypothermic treatment of drone brood can significantly reduce the infestation, but not prevent it. A negative side effect of the systematic drone brood removal is the favoritism, i.e. a selection, of those mites that visit the worker brood.

The hyperthermic treatment according to Engels and Rosenkranz is a non-toxic and acid-free method to combat the varroa mite. This is based on the knowledge that varroa mites, unlike bee pupae, are not as resistant to increased temperatures. During the treatment, the capped bee brood is specifically heated. Exact maintenance of the temperature, slow heating and guarantee of the relative humidity are decisive for the success of the treatment.

Another non-toxic and acid-free method is the quite new honeycomb trap method according to Woköck / Bojaschewsky. This method is more labor-intensive, but the development of resistance on the part of the mites is excluded, while natural selection limits the mites' ability to reproduce.

Research is currently being carried out into ways of using the book scorpion ( Chelifer cancroides ) and other pseudoscorpion species to combat the varroa mite in beehives. It was confirmed by observations that pseudoscorpions attack the mites as prey. A New Zealand working group has developed a method to use PCR to prove that the scorpion has eaten the mite, even if the process was not directly observed. The actual experiments to control Varroa by chelifers and other pseudoscorpions have so far (as of 2016) produced negative results.

See also

literature

Individual evidence

  1. ↑ Diana Sammataro, Uri Gerson, Glen Needham: Parasitic mites of honey bees: Life history, implications, and impact. In: Annual Review of Entomology. Vol. 45, 2000, pp. 519-548, doi: 10.1146 / annurev.ento.45.1.519 .
  2. ↑ AC Oudemans: Acarologische Aanteekeningen XIII. In: Entomological Reports. , Vol. 1, 1904, pp. 169-174.
  3. ↑ Friedrich Ruttner, Heinz Hänel: Active defense against Varroa mites in a Carniolan strain of honeybee (Apis mellifera carnica Pollmann). In: Apidology . Vol. 23, No. 2, 1992, pp. 173-187, digital version (PDF; 2.37 MB) .
  4. ↑ a b c d e f Peter Rosenkranz, Pia Aumeier, Bettina Ziegelmann: Biology and control of Varroa destructor. In: Journal of Invertebrate Pathology. Vol. 103, Supplement, 2010, pp. S96-S119, doi: 10.1016 / j.jip.2009.07.016 .
  5. ↑ MD Definado, EW Baker: Varroidae, a new family of mites on honey bees (Mesostigmata; Acarina). In: Journal of the Washington Academy of Sciences. Vol. 64, No. 1, 1974, ISSN  0043-0439 , pp. 4-10, digitized .
  6. ↑ G. Donzè, M. Herrmann, B. Bachofen, PRM Guerin (1996): Effect of mating frequency and brood cell infestation rate on the reproductive success of the honeybee parasite Varroa jacobsoni. In: Ecological Entomology 21: 17-26. doi: 10.1111 / j.1365-2311.1996.tb00261.x
  7. ↑ Denis L. Anderson, John WH Trueman: Varroa jacobsoni (Acari: Varroidae) is more than one species. In: Experimental & Applied Acarology. Vol. 24, No. 3, 2000, pp. 165-189, doi: 10.1023 / A: 1006456720416 .
  8. ↑ Lilia I. de Guzman, Thomas E. Rinderer: Identification and comparison of Varroa species infesting honey bees. In: Apidology. Vol. 30, No. 2/3, 1999, pp. 85-95, doi: 10.1051 / apido: 19990201 .
  9. ↑ Michel Solignac, Jean-Marie Cornuet, Dominique Vautrin, Yves Le Conte, Denis Anderson, Jay Evans, Sandrine Cros-Arteil, Maria Navajas: The invasive Korea and Japan types of Varroa destructor, ectoparasitic mites of the Western honeybee (Apis mellifera) , are two partly isolated clones. In: Proceedings of the Royal Society of London . Series B: Biological Sciences. Vol. 272, No. 1561, 2005, pp. 411-419, doi: 10.1098 / rspb.2004.2853 .
  10. ↑ a b Elke Genersch: Honey bee pathology: current threats to honey bees and beekeeping. In: Applied Microbiology and Biotechnology . Vol. 87, No. 1, 2010, pp. 87-97, doi: 10.1007 / s00253-010-2573-8 .
  11. ↑ Friedrich Ruttner, Wolfgang Ritter: The penetration of Varroa jacobsoni into Europe in retrospect. In: General German beekeeping newspaper. Vol. 14, No. 5, 1980, pp. 130-134.
  12. ↑ Ramsey SD, Ochoa R, Bauchan G, Gulbronson C, Mowery JD, Cohen A, Lim D, Joklik J, Cicero JM, Ellis JD, Hawthorne D, vanEngelsdorp D: Varroa destructor feeds primarily on honey bee fat body tissue and not hemolymph . In: Proceedings of the National Academy of Sciences USA Vol. 116, No. 5, 2019, pp. 1792–1801, doi: 10.1073 / pnas.1818371116 .
  13. ↑ Elke Genersch, Werner von der Ohe, Hannes Kaatz, Annette Schroeder, Christoph Otten, Ralph Büchler, Stefan Berg, Wolfgang Ritter, Werner Mühlen, Sebastian Gisder, Marina Meixner, Gerhard Liebig , Peter Rosenkranz: The German bee monitoring project: a long term study to understand periodically high winter losses of honey bee colonies. In: Apidology. Vol. 41, No. 3, 2010, pp. 332-352, doi: 10.1051 / apido / 2010014 .
  14. ↑ Main cause for the great bee deaths found . In: Welt Online , March 24, 2011.
  15. ↑ Richard Friebe : People of the bees, quo vadis? In: faz.net , April 6, 2011.
  16. ↑ Lars Straub, Geoffrey R. Williams, Beatriz Vidondo, Kitiphong Khongphinitbunjong, Gina Retschnig, Annette Schneeberger, Panuwan Chantawannakul, Vincent Dietemann, Peter Neumann: Neonicotinoids and ectoparasitic mites synergistically impact honeybees. In: Scientific Reports. 9, 2019, doi : 10.1038 / s41598-019-44207-1 .
  17. ↑ Peter Rosenkranz: Honey bee (Apis mellifera L.) tolerance to Varroa jacobsoni Oud. in South America. In: Apidology. Vol. 30, No. 2/3, 1999, pp. 159-172, doi: 10.1051 / apido: 19990206 .
  18. ↑ The Dark Bee - The Sicilian Bee , on: nordbiene.de
  19. ↑ Where varroa-tolerant colonies arise , on: mellifera.de
  20. ↑ Apis mellifera sicula , on: imkerpedia.nl (Dutch)
  21. ↑ Barbara Locke: Host-parasite adaptations and interactions between honey bees, varroa mites and viruses (= Acta Universitatis Agriculturae Sueciae. 57). Swedish University of Agricultural Sciences - Department of Ecology, Uppsala 2012, ISBN 978-91-576-7704-4 (Doctoral Thesis; online ).
  22. ↑ Varroa resistance - Natural behavior to withstand varroa , on: Arista Bee Research (aristabeeresearch.org)
  23. ^ A Sustainable Approach to Controlling Honey Bee Diseases and Varroa Mites . SARE. Retrieved July 13, 2020.
  24. ↑ Victoria Gill: Genetic weapon developed against honeybee-killer . In: BBC News , December 22, 2010. Retrieved July 13, 2020. 
  25. ↑ author = Greg Hunt, J. Krispn Given, Jennifer M. Tsuruda, Gladys K. Andino: Breeding Mite-Biting Bees to Control Varroa . March 23, 2016.
    Greg Hunt, J. Krispn Given, Jennifer M. Tsuruda, Gladys K. Andino: Breeding Mite-Biting Bees to Control Varroa . Bee Culture. April 2016. (PDF)
  26. ↑ Nadja Podbregar: Honey bees: With targeted breeding against the Varroa mite , on: natur.de from July 10, 2020, source: Julius-Maximilians-Universität Würzburg
  27. ↑ Tolerance breeding in the apiary , Julius Maximilians University of Würzburg, Chair of Behavioral Physiology and Sociobiology, July 7, 2020
  28. ↑ Edlinger Varroa indicator
  29. ↑ ADIZ 08/2011 pp. 7-9.
  30. ↑ ADIZ 1987 and Beekeeper Friend 1991 pp. 19–22.
  31. ↑ Mode of action of formic acid
  32. ↑ Press release of the University of Hohenheim from January 12, 2018
  33. ↑ Austrian Agency for Health and Food Safety GmbH: Varroa fight ( memento of the original from March 25, 2016 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , 2nd edition 2015, accessed on March 24, 2016 @1@ 2Template: Webachiv / IABot / www.ages.at
  34. ↑ Bavarian State Institute for Viticulture and Horticulture: Approved Varroa Control Agents , (as of June 30, 2014)
  35. ↑ Varroa under control. (PDF) Arbeitsgemeinschaft der Bienenforschung eV, 2007, p. 8 , accessed on March 28, 2015 (Deutscher Landwirtschaftsverlag GmbH, Berlin; biotechnical control methods).
  36. ^ J. Weiß, lecture at Pamina-Gymnasium Herxheim on October 7, 2014
  37. ↑ Wolfgang Wimmer: Practical manual of the thermal Varroa control. 2nd Edition. Ecodesign Company, Vienna 2015, ISBN 978-3-200-03995-7 .
  38. ↑ Olga Cadosch: How does hyperthermia work? In: Swiss bee newspaper. Vol. 137, No. 5, 2014, pp. 16–17, digitized version (PDF; 1.23 MB) ( memento of the original from April 6, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . @1@ 2Template: Webachiv / IABot / www.varroahyperthermie.ch
  39. ↑ Hans-Diethelm Woköck, Manfred Bojaschewsky: The collecting honeycomb method for the treatment of varoatosis. online ( Memento from February 22, 2013 in the web archive archive.today ).
  40. ↑ The Beenature Project. Torben Schiffer, Otto Hahn School, Hamburg
  41. ↑ Ron F. van Toor, Shirley E. Thompson, Donna M. Gibson, Grant R. Smith (2015): Ingestion of Varroa destructor by pseudoscorpions in honey bee hives confirmed by PCR analysis. Journal of Apicultural Research 54 (5), online before print. doi : 10.1080 / 00218839.2016.1184845
  42. ↑ Ron van Toor, James Pinfold: Can chelifers be made to control varroa mites in beehives? Poster Presentation, 2016 New Zealand Apiculture Conference, Rotorua. PDF

Web links

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